Somali Plate Undocking Kinematics

点击翻译按钮获取中文摘要

9706356 Bilham East Africa is breaking apart as a result of plate tectonic activity. The goal of this project is to measure the velocity of east Africa relative to west Africa across the African Rift zone. The speed and direction of easternmost Africa determines the productivity of volcanoes and earthquakes near the rift zone, and the formative kinematics of sedimentary oil reservoirs within the rift. The PI and collaborators hypothesize that east Africa slips NE in the same direction as India and Arabia. In 1991 they discovered from measurements of historic markers in Ethiopia, that Somalia is not moving to the SE more than 1 m per 1000 years (a very slow rate), but they were unable to estimate its NE component of slip. In 1997 the team will re-measure the very precise markers that were installed in 1991 in Ethiopia, and measure a 90-year-old British survey in Uganda, both of which are sensitive to NE motion. The measurements employ Global Positioning System (GPS) methods accurate to 3 mm, permitting estimation of 1997-1991 velocities to an accuracy of 0.7 mm/year, and 1997-1907 velocities which include less accurate traditional survey methods, to approximately 2 mm/year. ***